Molded rubber dashpot



1960 M. SMITLE Y ErAL 2,947,509

MOLDED RUBBER DASHPOT Filed Sept. 17, 1956 firm IN V EN TORS 4442/0 A 544/745) 22 4 Trap/VF) United States Patent MOLDED RUBBER DASHPOT Marion L. Smitley, Huntington Woods, and Melvin F. Sterner, Bloomfield Hills, Mich, 'assiguors to Holley arburetor Company, Van Dyke, Mich., a corporation of Michigan Filed Sept. 17, 1956, Ser. No. 610,141

4 Claims. (Cl. 251-48) This invention relates generally to motion retarding devices, and more particularly to a dashpot device for carburetors and the like.

A dashpot is normally incorporated in carburetors for vehicles fitted with automatic transmissions or power brakes in combination with an overdrive transmission as an anti-stall device to prevent the engine from being loaded with fuel when the accelerator pedal is suddenly depressed and released. It accomplishes this by slowing the closing rate of the throttle as it approaches the idle position so that the engine can dissipate the raw fuel discharged into the intake manifold by the accelerating pump.

Dashpots presently employed usually comprise a pair of chambers formed by securing a pair of dish-shaped stampings together with a flexible diaphragm between them. One chamber has a spring urging the diaphragm toward the other chamber, the latter having a stem attached to the center of the diaphragm and extending through a guide sleeve to the outside of the dashpot. The spring side of the dashpot is secured to the carburetor in a manner so that the stem may be engaged by the throttle lever when it approaches idle position. A valve in the diaphragm permits air to bleed quickly from one chamber to the other as the throttle is opened and permits the stem to follow the throttle lever. A restriction in parallel with the valve retards the movement of the diaphragm and stem as the throttle is returned to idle, at which time 'the valve is closed.

While the typical dashpot structure described above has been generally satisfactory in operation, there are some objections to it. In the first place, it contains a number of parts so that it is relatively expensive to manufacture, particularly in view of the relatively simple purpose it serves. Secondly, these parts sometimes become dirty or damaged, which results in sticking and other malfunctions of the dashpot.

It is now proposed to provide an extremely simple and inexpensive dashpot structure which functions just as well as the present more complicated and expensive structures and which cannot become damaged or dirty like present structures. This is accomplished by providing a one-piece construction in which the dashpot comprises a hollow, single-chamber resilient bulb having an open end adapted to be closed by the throttle lever, with an air bleed passage being provided in the throttle lever.

The objects and advantages of the invention will become apparent by reference to the following description and the drawings, wherein:

Fig. 1 is a side elevational view, with portions thereof cut away and in cross-section, of a carburetor embodying the invention.

Fig. 2 is an enlarged fragmentary view of the left-hand portion of Fig. 1 further illustrating the invention.

Referring to the drawings in greater detail, a carburetor having a throttle body portion 12 is provided with a throttle shaft 14 on which a throttle plate (not shown) snares Patented Aug. 2, 1960 is mounted within the throttle body. A throttle lever 16 is fixed on the shaft 14.

Depression of the accelerator pedal (not shown) pulls the linkage 18 pivoted on the throttle lever 16 to the right; this rotates the throttle lever 16, the shaft 14 and the throttle plate in a clockwise direction to open the throttle plate.

The link 22 is pivoted to the throttle lever 16 and to the accelerating pump rod 20 so that opening the throttle plate actuates the accelerating pump to discharge an additional amount of raw fuel into the intake manifold.

Releasing the accelerator pedal allows a spring (not shown) to move the link 18 to the left and close the throttle plate by counter clockwise rotation of the lever 16.

A bracket 24 is secured to the throttle body 12 by any suitable means such as the screw 26; the opposite end 28 of the bracket is formed so as to be approximately normal to the movement of the end 30 of the lever 16 when it approaches the idle position.

The dashpot assembly 31 comprises a hollow, singlechamber, resilient bulb-shaped member 32 having a short tubular projection 34 terminating in a relatively soft sealing bead 36 and being secured in any suitable well known manner to a bolt 38. In Fig. l, for instance, the member 32 is merely bonded to the head 40 of the bolt 38; in Fig. 2 it is formed With an annular internal recess 42 adapted to receive the button-like projection 44 extending from the head 40.-

The assembly 31 is secured to the end 28 of the bracket 24 as shown. Alternatively, the member 32 may be secured directly to the bracket 24.

The member 32 may be constructed from any suitable resilient material, such as rubber, for example, that has suh'icient ability to quickly resume its original position under any conditions after repeated deformation.

A dashpot adjustment screw 46 threaded into the end 30 of the lever 16 is provided with a flat head 48 having an air bleed passage 50 extending angularly approximately from the top center thereof to the underside thereof adjacent to the threaded portion. The screw 46 is adjusted so that the head 48 will engage the bead 36 at any desired position of the throttle lever 16 aproaching idle position.

In Fig. l, the throttle lever 16 is shown in off-idle position, as it would be on initial depression of the accelerator pedal or on release of the accelerator pedal and return of the throttle lever 16 to a position approaching idle. It will be noted that the member 32 is in its free undeformed position, with the bead 36 aligned with the head 48 of the screw 46.

From the position shown in Fig. 1, the lever 16 will continue its unimpeded counter-clockwise rotation until the head 48 engages the bead 36, at which time it will begin to compress or deform axially the member 32, as shown in Fig. 2. The remaining few degrees of throttle lever travel to idle position is thus slowed up to a rate governed mainly by the compressed air bleeding through the passage 50 to atmosphere. It is apparent, however, that the design of the member 32, in addition to the size of passage 50, may be varied to modify the rate of final closure of the throttle.

When the throttle is opened again, the member 32 immediately returns to its free position shown by Fig. 1 until the throttle is closed again.

It is apparent that the structure described above provides a dashpot that is as eiiective as present structures, yet free of any possibility of malfunction and much less expensive. The invention is adaptable to applications other than carburetors, and modifications may be made therein without exceeding the scope thereof, as limited in the following claims.

What is claimed is:

1. A dashpot for a fuel control having a movable throttle lever, comprising a generally globular hollow resilient body having a tubular extension and being secured at the end thereof opposite said-extension to said control said body having but a single opening at the end of said extension, said throttle lever having a portion adapted to close said opening and to compress said body axially when said throttle lever-approaches said body, said portion having an air bleed passage therein to restrict'tbe escape of the air compressed within said body, said dashpot being adapted by reason of its configuration to provide one rate of lever movement during initial compression of said bodyand a slower rate of lever movement during final compression of said body.

2. A dashpot for a fuel control having a movable throttle lever, comprising a generally globular hollow resilient body with a tubular extension of lesser diameter than said body, said body being adapted to resist deformation and being secured with respect to said control, said body having only one opening at the end of said extension, said throttle lever having an adjustable member as sociated therewith adapted to seal said opening and to progressively compress said body when said throttle lever approaches one extreme position, said adjustable member having a small air bleed passage restricting the escape of the air compressed within said body, said dashpot providing by reason of its configuration for one rate of lever movement due to the initial compression of said body and a slower rate of lever movement due to the air cushion effect on final compression of said body.

3. A device for retarding movement of a body'toward a support, comprising a generally globular hollow resilient member secured in the path of travel of said body, said hollow member having a hollow projection of lesser dimension than said member and a single opening at the .end of said projection and opposite the secured end of said member, said body having an adjustable portion adapted to seal said opening and compress said hollow member and having a passage therein communicating between said opening and atmosphere to permit air in said compressed hollow member to escape at a controlled rate, said dashpot being adapted by reason of its configuration to permit a faster rate of movement of said body toward said support on initial compression of said hollow member and a slower rate-ofsaid movement upon compression of the air in said hollow member, the adjust- -rnent of said portion of saidbody determining the initial ciated with one of said members to restrictthe escape of air during compression of the resilient member whereby said dashpot, because of its configuration, provides one rate of movement of said contro-lmember during initial compression of the resilient member-and a slower rate of movement of said control memberduring final compression of the resilient member.

References Cited in the file of this patent UNITED STATES PATENTS 431,387 McHugh July: 1, 1890 831,694 -,Wulf' i Sept. '25, 1906 1,830,877 Kirby Nov. 10,1931

2,068,948 Freeman Jan."26, 1937 2,215,953 Birr Sept. 24, 1940 2,759,698 Jorgensen .Aug. 21,;1956 

